Compile 6.4.2 under Redhat5.1

Compile 6.4.2 under Redhat5.1

I ran configure using the 'with-x' option in configure and got an 
warning:
'X11 library '-lX11' could not be found so TK support will be disabled'
where or what rpm is the -lX11 library under redhat 5.1?

Also,
I need to compile postgres with storage blocks greater than 8K so I 
can use the polygon type with large polygons.
What file and what define in the source code do I modify to 
increase the storage block size?



Regards,
Kenneth R. Mort  
TreeTop Research
Brooklyn, NY, USA